1636038 - 2.64% glterrain (windows10-64-shippable-qr) regression on push 4933e4b66edb70f5b8f682abc6025e9f50f14e4b (Thu April 23 2020)

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect)

Description

[Alexandru Ionescu (needinfo me) [:alexandrui]]

Perfherder has detected a talos performance regression from push 4933e4b66edb70f5b8f682abc6025e9f50f14e4b. As author of one of the patches included in that push, we need your help to address this regression.

Regressions:

3% glterrain windows10-64-shippable-qr opt e10s stylo 1.61 -> 1.65

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests. Please follow our guide to handling regression bugs and let us know your plans within 3 business days, or the offending patch(es) will be backed out in accordance with our regression policy.

For more information on performance sheriffing please see our FAQ.

Comment 1

[Nicolas Silva [:nical]]

Attachment: Bug 1636038 - Only rebuild the scene if the a displaylist or root pipeline was updated. r=gw

This reverts to the behavior before https://phabricator.services.mozilla.com/D71781 which introduced a talos regression.

Comment 2

[Nicolas Silva [:nical]]

The attached patch should fix it.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4d547aaf7f55
Only rebuild the scene if the a displaylist or root pipeline was updated. r=gw

Comment 4

[Nicolas Silva [:nical]]

This will need a beta uplift.

Comment 5

[Cristian Brindusan [:cbrindusan]]

https://hg.mozilla.org/mozilla-central/rev/4d547aaf7f55

Comment 6

[Alexandru Ionescu (needinfo me) [:alexandrui]]

== Change summary for alert #25899 (as of Tue, 12 May 2020 03:53:59 GMT) ==

Regressions:

3% glterrain windows10-64-shippable-qr opt e10s stylo 1.59 -> 1.63

Please ignore the following improvement as it is an outliar:

10% glterrain windows10-64-shippable-qr opt e10s stylo 1.83 -> 1.64

For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=25899

Comment 7

[Nicolas Silva [:nical]]

3% glterrain windows10-64-shippable-qr opt e10s stylo 1.59 -> 1.63

I just don't believe this to be accurate. The patch is very simple and strictly reduces the amount of computation happening (by quite a lot).

Comment 9

[BugBot [:suhaib / :marco/ :calixte]]

The patch landed in nightly and beta is affected.
:nical, is this bug important enough to require an uplift?
If not please set status_beta to wontfix.

For more information, please visit auto_nag documentation.

Comment 10

[Nicolas Silva [:nical]]

Comment on attachment 9146450 [details]
Bug 1636038 - Only rebuild the scene if the a displaylist or root pipeline was updated. r=gw

Beta/Release Uplift Approval Request

• User impact if declined: Significant performance regression
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Simple patch that reverts to a previous well tested behavior.
• String changes made/needed: None.

Comment 11

[Pascal Chevrel:pascalc]

Comment on attachment 9146450 [details]
Bug 1636038 - Only rebuild the scene if the a displaylist or root pipeline was updated. r=gw

Low risk perf fix,, approved for 77 beta 7, thanks.

Comment 12

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/releases/mozilla-beta/rev/e402ea5e06ef